1. Technical Field
The present invention relates to new macrocyclic systems of porphyrazine-type and their metal derivatives, characterized by the presence of heteroatoms at the periphery of the macrocyclic ring.
This new series of compounds of porphyrazine-type supplement the class of compounds so called xe2x80x9cphthalocyaninesxe2x80x9d (xe2x80x9cThe Phthalocyaninesxe2x80x9d, F. H. Moser, A. L. Thomas, Eds.; CRC Press, Boca Raton, Fla., Vol. 1 and II, 1983), comprising the phthalocyanine and the metal derivatives thereof, already known since the 1930s (R. P. Linstead and al., J. Chem. Soc., 1936, 1016, and later works), as laboratory synthetic products and having a molecular structure bringing to mind that of analogue synthetic and natural porphyrines (xe2x80x9cThe porphyrinesxe2x80x9d, D. Dolphin, Ed.; Acad. Press Inc.; New York; Vols. I-VII (1979)).
2. Background Art
It is well known from the last 50 years literature that the phthalocyanines as such and as the derivatives thereof having various substituents on the peripheral benzene rings, have been the object of a large interest both in basic researches and for researches of applicative type (xe2x80x9cPhthalocyanines: Properties and Applicationsxe2x80x9d, C. C. Leznoff, A.B.P. Lever, Eds., VCH Publ., New York, Vols. I-IV (1989-1996). They are intensively studied as special materials for forming thin films, for applications in the fields of sensors, electric conductivity and semiconductivity, electrochromics, liquid crystals, catalysis, non-linear optic properties, graphic reproduction, but also for practical interest aspects, such as the preparation of inks and dyes for textiles, to mention only some among those of present major interest. It ensues that the phthalocyanines are manufactured and put into the market by big chemical industries and by industries specialized in research purposes, among which Carlo Erba, Aldrich (U.S.A.) and Fluka (Germany).
Valid alternatives do not seem to have resulted from attempts made in the last years to supplement the pthalocyanines with new classes of compounds, similar in molecular and electronical structure, but having innovative elements such as to allow an equal broad utilization in the development of basic research and new specialistic applications.
The new phthalocyanine-like systems, according to the present invention, open the possibility of new scientific investigations, with potential capabilities of broader technological applications in fields of great importance both for the basic research and industrial field utilization.
Object of the present invention are macrocyclic porphyrazine-type compounds and the metal derivatives thereof, characterized by the fact of comprising rings of heterocycle type at the periphery of the inner porphyrazine fragment.
The new macrocyclic compounds according to the present invention have, at the periphery of the inner porphyrazine fragment, a ring of selenodiazole type, and they show the following structural formula (I) 
in which X is Se.
A further object of the present invention are the metal derivatives of the above mentioned molecules.
Hereinafter the molecule with the thiadiazole ring and the metal derivatives thereof will be also indicated as I-a, whereas the molecule according to the invention with selenodiazole ring and the metal derivatives thereof will be also indicated as I-b.
An additional object of the present invention is a process for the preparation of the macrocyclic compounds (1) and the metal derivatives thereof, characterized by cyclotetramerizating the monomers 3,4-dicyano-1,2,5-thiadiazole, or 3,4-dicyano-1,2,5-selenodiazole in an organic solvent by reaction with Mg(II) as a template, in the form of alcohoxylate, in the presence of a small amount of I2 as a catalyst or by reaction with inorganic salts, eventual extraction of the metal by treatment with strong acids from the formed complexes to obtain tetrakis(thiadazole)porphyrazine, or tetrakis(selenodiazole)porphyrazine, and eventual treatment of these compounds by a metallorganic or inorganic salt to obtain the metal derivatives thereof different from the previously extracted metals.
In the process according the present invention, the inorganic salt used for the cyclotetramerization can be a salt of a metal selected from the group comprising Mg(II), Al(III), Ga(III) and In(III). The extraction of the metal from the formed complexes can be obtained with strong acids selected from the group comprising acetic acid, trifluoroacetic acid and sulphuric acid.
In a particular embodiment of the present invention, the preparation of a specific compound of formula (1) and, from that, of a series of metal derivatives, is carried out starting from monomer species comprising 3,4-dicyano-1,2,5-thiadiazole (DCTD) and from the corresponding selenium monomer (DCSeD), obtained from commercially available (Carlo Erba, Aldrich, Fluka) diaminomaleodinitryl 
(DMN), and thionyl chloride respectively (yield 80-90%), following a process already described in the literature (G. Ribaldone, R. Grecu, Germ. Pat. 2651604 (1977), Chem. Abst., 87, 1977, 135344) and SeO2. For DCSeD, the same reagents (DMN and SeO2) have been used by Shew (D. Shew, Diss. Abstr., 20, 1959, 1593; Chem. Abstr. 54, 4548a). We have observed that by stirring DMN with SeO2 in CH2Cl2, DCSeD was obtained with a practically theoretical yield (97-100%). Some authors instead prepared DCSeD from diiminosuccinonitryl and SeO2, but with a lower yield (H. W. Roesky, T. Gries, H. Hofman, J. Schimkowiak, P. G. Jones, K. Meyer-Bxc3xa4se, G. M. Sheldrik, Chem. Ber., 119, 1986, 366).
The process of cyclotetramerization of the monomers DCTD and DCSeD can be operated by reaction with Mg(II) as a template in alkoxylate form (such as propoxylate, butoxylate), in the presence of small amounts of I2 as a catalyst. The metal can be extracted from the Mg(II) complex by treatment with strong acids (CH3COOOH, CF3COOH, H2SO4) to obtain the compound (1). The preparation of other metal derivatives can proceed from the compound (1) by selecting a new metal respectively in form of an organic or inorganic salt (such as acetate, chloride, sulphate and the like) and under suitable conditions of temperature and reaction means (dimethylsulphoxide, pyridine, quinoline, xcex3-picoline and the like). The reaction sequence, starting from DCTD, has the schema outlined as follows:
DCTD+Mg(OC3H7)2 xe2x86x92TTDPzMg.(solv.)
TTDPzMg.(solv.)xe2x86x92TTDPzH2.(solv.)
TTDPzH2.(solv.)+M(II)xe2x86x92TTDPzM.(solv.)
(py,DMSO)
A similar schema applies to the case of DCSeD.
The new macrocyclic compounds according to the invention show in common with the phtalocyanine class: a) the central porphyrazine fragment; b) the substantially square, planar structure of the whole macrocycle compound, in view of the peculiar structural characteristics of the thiadiazole and selenodiazole rings; c) wide delocalization of xcfx80 electrons which, is similarly to phthalocyanines, extend throughout the molecular system. It is to be noted that, as in the thiadiazole and selenodiazole rings the number of xcfx80 electrons is the same as that in the benzene ring, the new molecular systems provided in the present invention are isoelectronic to the phthalocyanines under this aspect.
The basic and interesting feature distinguishing the compounds described in the present invention from the phthalocyanine class resides in the presence of heteroatoms (N, S, Se) at the periphery of the macrocyclic ring. The spectroscopic behaviour in the visible UV region of the new systems shows that such presence produces differentiation features in the distribution of the xcfx80 electron charge inside the molecular system of the macrocycles. In addition, the S and Se atoms, having xe2x80x9csoftxe2x80x9d atom characteristics, represent a strong novelty item. In fact they necessarily produce a peculiar situation of the contacts of one molecule to the other in the solid state. This has been shown to be of extreme importance in the field of the phthalocyanines as materials having, to say, electric conductivity properties, as such or after undergoing an oxidative doping. The additional advantageous property of the new class of macrocycle compounds is the general tendency thereof to attract molecules or metal ions at the periphery of the macrocycle ring essentially in view of the presence of the nitrogen atoms. For instance both of the macrocycle ligands of formula (I), and the respective metal derivatives are generally obtained in the air in the form of hydrates as a consequence of an engagement of H2O molecules at the macrocycle periphery. In addition this has influence on the solid state or of any other nature crystal, and on the possible interactions between the macrocycles in the solid state itself.
Herein before a general description of the invention has been presented. A more detailed description of specific embodiments will be given hereinafter with reference to the following examples, aiming at enhancing the objects, features and advantages of the invention. In particular the examples show some methods concerning the derivatives containing the thiadiazole ligand. Similar methods also apply to the corresponding products containing selenium.